From 68caf1727f809804b4fcfcefd475490fef9d304d Mon Sep 17 00:00:00 2001 From: Rafael Espindola Date: Sat, 7 Jun 2014 04:12:35 +0000 Subject: Revert 209903 and 210040. The messages were "PR19753: Optimize comparisons with "ashr exact" of a constanst." "Added support to optimize comparisons with "lshr exact" of a constant." They were not correctly handling signed/unsigned operation differences, causing pr19958. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210393 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/InstCombine/InstCombineCompares.cpp | 40 ---------------------- 1 file changed, 40 deletions(-) (limited to 'lib/Transforms') diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index 13a5cd96f7..d98f966f8c 100644 --- a/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -2318,32 +2318,6 @@ static bool swapMayExposeCSEOpportunities(const Value * Op0, return GlobalSwapBenefits > 0; } -// Helper function to check whether Op represents a lshr/ashr exact -// instruction. For example: -// (icmp (ashr exact const2, A), const1) -> icmp A, Log2(const2/const1) -// Here if Op represents -> (ashr exact const2, A), and CI represents -// const1, we compute Quotient as const2/const1. - -static bool checkShrExact(Value *Op, APInt &Quotient, const ConstantInt *CI, - Value *&A) { - - ConstantInt *CI2; - if (match(Op, m_AShr(m_ConstantInt(CI2), m_Value(A))) && - (cast(Op)->isExact())) { - Quotient = CI2->getValue().sdiv(CI->getValue()); - return true; - } - - // Handle the case for lhsr. - if (match(Op, m_LShr(m_ConstantInt(CI2), m_Value(A))) && - (cast(Op)->isExact())) { - Quotient = CI2->getValue().udiv(CI->getValue()); - return true; - } - - return false; -} - Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { bool Changed = false; Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); @@ -2465,20 +2439,6 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { return new ICmpInst(I.getPredicate(), A, B); } - // PR19753: - // (icmp (ashr exact const2, A), const1) -> icmp A, Log2(const2/const1) - // Cases where const1 doesn't divide const2 exactly or Quotient is not - // exact of log2 are handled by SimplifyICmpInst call above where we - // return false. Similar for lshr. - { - APInt Quotient; - if (checkShrExact(Op0, Quotient, CI, A)) { - unsigned shift = Quotient.logBase2(); - return new ICmpInst(I.getPredicate(), A, - ConstantInt::get(A->getType(), shift)); - } - } - // If we have an icmp le or icmp ge instruction, turn it into the // appropriate icmp lt or icmp gt instruction. This allows us to rely on // them being folded in the code below. The SimplifyICmpInst code has -- cgit v1.2.3